The present invention relates to a file management system having a large capacity memory for storing long data, and more particularly to a data processing method and an apparatus therefor in a system for managing a multimedia data base, a map information data base and a knowledge data base in which character texts, figures and image data are stored.
In the system which handles long data such as character texts, figures and image data, since a logical record length of data is increased and an amount of data to be transferred between an input/output buffer set in a main memory in a central processing unit for processing data and an external memory unit for storing data is increased, a sufficient access performance is not obtained due to a limitation of a data transfer rate. Further, by repeating update, addition and deletion of expanded records, invalid areas are scatteringly formed in a file to thereby deteriorate a space efficiency of the file.
In this connection, JP-A-1-106217 discloses a technique that long data is divided and the divided data are stored in a plurality of secondary memory units in parallel. In this technique, the long data is divided to form divided files and information relative to memory locations of the divided files in the secondary memory units is stored in one of the divided files. When the long data is read out, the information relative to the memory location is read out from one of the divided files and the divided files in the secondary memory units indicated by the information are read out in parallel to restore the long data. When the data is updated, the restored data is updated and the updated data is divided again to store in the secondary memory units.
Further, JP-A-2-52305 discloses a partially updating method of image data in which in an image file apparatus for storing a document such as a drawing as an image file, an inputted document is divided into a predetermined number of divided image units to be stored and when any modification occurs in the document, only a divided image unit having contents which are to be modified is modified and stored again. In this technique, when the modification occurs, the whole image is not stored again and accordingly the image file can be updated at high speed.